1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.log4j;
19
20 import org.apache.log4j.helpers.OptionConverter;
21 import org.apache.log4j.helpers.PatternConverter;
22 import org.apache.log4j.pattern.BridgePatternConverter;
23 import org.apache.log4j.spi.LoggingEvent;
24
25
26 // Contributors: Nelson Minar <nelson@monkey.org>
27 // Anders Kristensen <akristensen@dynamicsoft.com>
28
29 /**
30 * This class is an enhanced version of org.apache.log4j.PatternLayout
31 * which was originally developed as part of the abandoned log4j 1.3
32 * effort and has been available in the extras companion.
33 * This pattern layout should be used in preference to
34 * org.apache.log4j.PatternLayout except when compatibility
35 * where PatternLayout has been extended either through subclassing
36 * or alternative pattern parsers.
37 *
38 *
39 * <p>A flexible layout configurable with pattern string. The goal of this class
40 * is to {@link #format format} a {@link LoggingEvent} and return the results
41 * in a {@link StringBuffer}. The format of the result depends on the
42 * <em>conversion pattern</em>.
43 * <p>
44 *
45 * <p>The conversion pattern is closely related to the conversion
46 * pattern of the printf function in C. A conversion pattern is
47 * composed of literal text and format control expressions called
48 * <em>conversion specifiers</em>.
49 *
50 * <p><i>Note that you are free to insert any literal text within the
51 * conversion pattern.</i>
52 * </p>
53
54 <p>Each conversion specifier starts with a percent sign (%) and is
55 followed by optional <em>format modifiers</em> and a <em>conversion
56 character</em>. The conversion character specifies the type of
57 data, e.g. category, priority, date, thread name. The format
58 modifiers control such things as field width, padding, left and
59 right justification. The following is a simple example.
60
61 <p>Let the conversion pattern be <b>"%-5p [%t]: %m%n"</b> and assume
62 that the log4j environment was set to use a EnhancedPatternLayout. Then the
63 statements
64 <pre>
65 Category root = Category.getRoot();
66 root.debug("Message 1");
67 root.warn("Message 2");
68 </pre>
69 would yield the output
70 <pre>
71 DEBUG [main]: Message 1
72 WARN [main]: Message 2
73 </pre>
74
75 <p>Note that there is no explicit separator between text and
76 conversion specifiers. The pattern parser knows when it has reached
77 the end of a conversion specifier when it reads a conversion
78 character. In the example above the conversion specifier
79 <b>%-5p</b> means the priority of the logging event should be left
80 justified to a width of five characters.
81
82 The recognized conversion characters are
83
84 <p>
85 <table border="1" CELLPADDING="8">
86 <th>Conversion Character</th>
87 <th>Effect</th>
88
89 <tr>
90 <td align=center><b>c</b></td>
91
92 <td>Used to output the category of the logging event. The
93 category conversion specifier can be optionally followed by
94 NameAbbreviator pattern.
95
96 <p>For example, for the category name "alpha.beta.gamma" the pattern
97 <b>%c{2}</b> will output the last two elements ("beta.gamma"),
98 <b>%c{-2}</b> will remove two elements leaving "gamma",
99 <b>%c{1.}</b> will output "a.b.gamma".
100
101 </td>
102 </tr>
103
104 <tr>
105 <td align=center><b>C</b></td>
106
107 <td>Used to output the fully qualified class name of the caller
108 issuing the logging request. This conversion specifier
109 can be optionally followed by <em>precision specifier</em>, that
110 is a decimal constant in brackets.
111
112 <td>Used to output the category of the logging event. The
113 category conversion specifier can be optionally followed by
114 NameAbbreviator pattern.
115
116 <p>For example, for the category name "alpha.beta.gamma" the pattern
117 <b>%c{2}</b> will output the last two elements ("beta.gamma"),
118 <b>%c{-2}</b> will remove two elements leaving "gamma",
119 <b>%c{1.}</b> will output "a.b.gamma".
120
121 <p><b>WARNING</b> Generating the caller class information is
122 slow. Thus, its use should be avoided unless execution speed is
123 not an issue.
124
125 </td>
126 </tr>
127
128 <tr> <td align=center><b>d</b></td> <td>Used to output the date of
129 the logging event. The date conversion specifier may be
130 followed by a set of braces containing a
131 date and time pattern strings {@link java.text.SimpleDateFormat},
132 <em>ABSOLUTE</em>, <em>DATE</em> or <em>ISO8601</em>
133 and a set of braces containing a time zone id per
134 {@link java.util.TimeZone#getTimeZone(String)}.
135 For example, <b>%d{HH:mm:ss,SSS}</b>,
136 <b>%d{dd MMM yyyy HH:mm:ss,SSS}</b>,
137 <b>%d{DATE}</b> or <b>%d{HH:mm:ss}{GMT+0}</b>. If no date format specifier is given then
138 ISO8601 format is assumed.
139 </td>
140 </tr>
141
142 <tr>
143 <td align=center><b>F</b></td>
144
145 <td>Used to output the file name where the logging request was
146 issued.
147
148 <p><b>WARNING</b> Generating caller location information is
149 extremely slow and should be avoided unless execution speed
150 is not an issue.
151
152 </tr>
153
154 <tr>
155 <td align=center><b>l</b></td>
156
157 <td>Used to output location information of the caller which generated
158 the logging event.
159
160 <p>The location information depends on the JVM implementation but
161 usually consists of the fully qualified name of the calling
162 method followed by the callers source the file name and line
163 number between parentheses.
164
165 <p>The location information can be very useful. However, its
166 generation is <em>extremely</em> slow and should be avoided
167 unless execution speed is not an issue.
168
169 </td>
170 </tr>
171
172 <tr>
173 <td align=center><b>L</b></td>
174
175 <td>Used to output the line number from where the logging request
176 was issued.
177
178 <p><b>WARNING</b> Generating caller location information is
179 extremely slow and should be avoided unless execution speed
180 is not an issue.
181
182 </tr>
183
184
185 <tr>
186 <td align=center><b>m</b></td>
187 <td>Used to output the application supplied message associated with
188 the logging event.</td>
189 </tr>
190
191 <tr>
192 <td align=center><b>M</b></td>
193
194 <td>Used to output the method name where the logging request was
195 issued.
196
197 <p><b>WARNING</b> Generating caller location information is
198 extremely slow and should be avoided unless execution speed
199 is not an issue.
200
201 </tr>
202
203 <tr>
204 <td align=center><b>n</b></td>
205
206 <td>Outputs the platform dependent line separator character or
207 characters.
208
209 <p>This conversion character offers practically the same
210 performance as using non-portable line separator strings such as
211 "\n", or "\r\n". Thus, it is the preferred way of specifying a
212 line separator.
213
214
215 </tr>
216
217 <tr>
218 <td align=center><b>p</b></td>
219 <td>Used to output the priority of the logging event.</td>
220 </tr>
221
222 <tr>
223
224 <td align=center><b>r</b></td>
225
226 <td>Used to output the number of milliseconds elapsed since the construction
227 of the layout until the creation of the logging event.</td>
228 </tr>
229
230
231 <tr>
232 <td align=center><b>t</b></td>
233
234 <td>Used to output the name of the thread that generated the
235 logging event.</td>
236
237 </tr>
238
239 <tr>
240
241 <td align=center><b>x</b></td>
242
243 <td>Used to output the NDC (nested diagnostic context) associated
244 with the thread that generated the logging event.
245 </td>
246 </tr>
247
248
249 <tr>
250 <td align=center><b>X</b></td>
251
252 <td>
253
254 <p>Used to output the MDC (mapped diagnostic context) associated
255 with the thread that generated the logging event. The <b>X</b>
256 conversion character can be followed by the key for the
257 map placed between braces, as in <b>%X{clientNumber}</b> where
258 <code>clientNumber</code> is the key. The value in the MDC
259 corresponding to the key will be output. If no additional sub-option
260 is specified, then the entire contents of the MDC key value pair set
261 is output using a format {{key1,val1},{key2,val2}}</p>
262
263 <p>See {@link MDC} class for more details.
264 </p>
265
266 </td>
267 </tr>
268
269 <tr>
270 <td align=center><b>properties</b></td>
271
272 <td>
273 <p>Used to output the Properties associated
274 with the logging event. The <b>properties</b>
275 conversion word can be followed by the key for the
276 map placed between braces, as in <b>%properties{application}</b> where
277 <code>application</code> is the key. The value in the Properties bundle
278 corresponding to the key will be output. If no additional sub-option
279 is specified, then the entire contents of the Properties key value pair set
280 is output using a format {{key1,val1},{key2,val2}}</p>
281 </td>
282 </tr>
283
284 <tr>
285 <td align=center><b>throwable</b></td>
286
287 <td>
288 <p>Used to output the Throwable trace that has been bound to the LoggingEvent, by
289 default this will output the full trace as one would normally
290 find by a call to Throwable.printStackTrace().
291 <b>%throwable{short}</b> or <b>%throwable{1}</b> will output the first line of
292 stack trace. <b>throwable{none}</b> or <b>throwable{0}</b> will suppress
293 the stack trace. <b>%throwable{n}</b> will output n lines of stack trace
294 if a positive integer or omit the last -n lines if a negative integer.
295 If no %throwable pattern is specified, the appender will take
296 responsibility to output the stack trace as it sees fit.</p>
297 </td>
298 </tr>
299
300 <tr>
301
302 <td align=center><b>%</b></td>
303
304 <td>The sequence %% outputs a single percent sign.
305 </td>
306 </tr>
307
308 </table>
309
310 <p>By default the relevant information is output as is. However,
311 with the aid of format modifiers it is possible to change the
312 minimum field width, the maximum field width and justification.
313
314 <p>The optional format modifier is placed between the percent sign
315 and the conversion character.
316
317 <p>The first optional format modifier is the <em>left justification
318 flag</em> which is just the minus (-) character. Then comes the
319 optional <em>minimum field width</em> modifier. This is a decimal
320 constant that represents the minimum number of characters to
321 output. If the data item requires fewer characters, it is padded on
322 either the left or the right until the minimum width is
323 reached. The default is to pad on the left (right justify) but you
324 can specify right padding with the left justification flag. The
325 padding character is space. If the data item is larger than the
326 minimum field width, the field is expanded to accommodate the
327 data. The value is never truncated.
328
329 <p>This behavior can be changed using the <em>maximum field
330 width</em> modifier which is designated by a period followed by a
331 decimal constant. If the data item is longer than the maximum
332 field, then the extra characters are removed from the
333 <em>beginning</em> of the data item and not from the end. For
334 example, it the maximum field width is eight and the data item is
335 ten characters long, then the first two characters of the data item
336 are dropped. This behavior deviates from the printf function in C
337 where truncation is done from the end.
338
339 <p>Below are various format modifier examples for the category
340 conversion specifier.
341
342 <p>
343 <TABLE BORDER=1 CELLPADDING=8>
344 <th>Format modifier
345 <th>left justify
346 <th>minimum width
347 <th>maximum width
348 <th>comment
349
350 <tr>
351 <td align=center>%20c</td>
352 <td align=center>false</td>
353 <td align=center>20</td>
354 <td align=center>none</td>
355
356 <td>Left pad with spaces if the category name is less than 20
357 characters long.
358
359 <tr> <td align=center>%-20c</td> <td align=center>true</td> <td
360 align=center>20</td> <td align=center>none</td> <td>Right pad with
361 spaces if the category name is less than 20 characters long.
362
363 <tr>
364 <td align=center>%.30c</td>
365 <td align=center>NA</td>
366 <td align=center>none</td>
367 <td align=center>30</td>
368
369 <td>Truncate from the beginning if the category name is longer than 30
370 characters.
371
372 <tr>
373 <td align=center>%20.30c</td>
374 <td align=center>false</td>
375 <td align=center>20</td>
376 <td align=center>30</td>
377
378 <td>Left pad with spaces if the category name is shorter than 20
379 characters. However, if category name is longer than 30 characters,
380 then truncate from the beginning.
381
382 <tr>
383 <td align=center>%-20.30c</td>
384 <td align=center>true</td>
385 <td align=center>20</td>
386 <td align=center>30</td>
387
388 <td>Right pad with spaces if the category name is shorter than 20
389 characters. However, if category name is longer than 30 characters,
390 then truncate from the beginning.
391
392 </table>
393
394 <p>Below are some examples of conversion patterns.
395
396 <dl>
397
398 <p><dt><b>%r [%t] %-5p %c %x - %m%n</b>
399 <p><dd>This is essentially the TTCC layout.
400
401 <p><dt><b>%-6r [%15.15t] %-5p %30.30c %x - %m%n</b>
402
403 <p><dd>Similar to the TTCC layout except that the relative time is
404 right padded if less than 6 digits, thread name is right padded if
405 less than 15 characters and truncated if longer and the category
406 name is left padded if shorter than 30 characters and truncated if
407 longer.
408
409 </dl>
410
411 <p>The above text is largely inspired from Peter A. Darnell and
412 Philip E. Margolis' highly recommended book "C -- a Software
413 Engineering Approach", ISBN 0-387-97389-3.
414
415 @author <a href="mailto:cakalijp@Maritz.com">James P. Cakalic</a>
416 @author Ceki Gülcü
417
418
419 @since 1.2.16 */
420 public class EnhancedPatternLayout extends Layout {
421 /** Default pattern string for log output. Currently set to the
422 string <b>"%m%n"</b> which just prints the application supplied
423 message. */
424 public static final String DEFAULT_CONVERSION_PATTERN = "%m%n";
425
426 /** A conversion pattern equivalent to the TTCCCLayout.
427 Current value is <b>%r [%t] %p %c %x - %m%n</b>. */
428 public static final String TTCC_CONVERSION_PATTERN =
429 "%r [%t] %p %c %x - %m%n";
430
431 /**
432 * Initial size of internal buffer, no longer used.
433 * @deprecated since 1.3
434 */
435 protected final int BUF_SIZE = 256;
436
437 /**
438 * Maximum capacity of internal buffer, no longer used.
439 * @deprecated since 1.3
440 */
441 protected final int MAX_CAPACITY = 1024;
442
443 /**
444 * Customized pattern conversion rules are stored under this key in the
445 * {@link org.apache.log4j.spi.LoggerRepository LoggerRepository} object store.
446 */
447 public static final String PATTERN_RULE_REGISTRY = "PATTERN_RULE_REGISTRY";
448
449
450 /**
451 * Initial converter for pattern.
452 */
453 private PatternConverter head;
454
455 /**
456 * Conversion pattern.
457 */
458 private String conversionPattern;
459
460 /**
461 * True if any element in pattern formats information from exceptions.
462 */
463 private boolean handlesExceptions;
464
465 /**
466 Constructs a EnhancedPatternLayout using the DEFAULT_LAYOUT_PATTERN.
467
468 The default pattern just produces the application supplied message.
469 */
470 public EnhancedPatternLayout() {
471 this(DEFAULT_CONVERSION_PATTERN);
472 }
473
474 /**
475 * Constructs a EnhancedPatternLayout using the supplied conversion pattern.
476 * @param pattern conversion pattern.
477 */
478 public EnhancedPatternLayout(final String pattern) {
479 this.conversionPattern = pattern;
480 head = createPatternParser(
481 (pattern == null) ? DEFAULT_CONVERSION_PATTERN : pattern).parse();
482 if (head instanceof BridgePatternConverter) {
483 handlesExceptions = !((BridgePatternConverter) head).ignoresThrowable();
484 } else {
485 handlesExceptions = false;
486 }
487 }
488
489 /**
490 * Set the <b>ConversionPattern</b> option. This is the string which
491 * controls formatting and consists of a mix of literal content and
492 * conversion specifiers.
493 *
494 * @param conversionPattern conversion pattern.
495 */
496 public void setConversionPattern(final String conversionPattern) {
497 this.conversionPattern =
498 OptionConverter.convertSpecialChars(conversionPattern);
499 head = createPatternParser(this.conversionPattern).parse();
500 if (head instanceof BridgePatternConverter) {
501 handlesExceptions = !((BridgePatternConverter) head).ignoresThrowable();
502 } else {
503 handlesExceptions = false;
504 }
505 }
506
507 /**
508 * Returns the value of the <b>ConversionPattern</b> option.
509 * @return conversion pattern.
510 */
511 public String getConversionPattern() {
512 return conversionPattern;
513 }
514
515
516 /**
517 Returns PatternParser used to parse the conversion string. Subclasses
518 may override this to return a subclass of PatternParser which recognize
519 custom conversion characters.
520
521 @since 0.9.0
522 */
523 protected org.apache.log4j.helpers.PatternParser createPatternParser(String pattern) {
524 return new org.apache.log4j.pattern.BridgePatternParser(pattern);
525 }
526
527
528 /**
529 Activates the conversion pattern. Do not forget to call this method after
530 you change the parameters of the EnhancedPatternLayout instance.
531 */
532 public void activateOptions() {
533 // nothing to do.
534 }
535
536
537 /**
538 * Formats a logging event to a writer.
539 * @param event logging event to be formatted.
540 */
541 public String format(final LoggingEvent event) {
542 StringBuffer buf = new StringBuffer();
543 for(PatternConverter c = head;
544 c != null;
545 c = c.next) {
546 c.format(buf, event);
547 }
548 return buf.toString();
549 }
550
551 /**
552 * Will return false if any of the conversion specifiers in the pattern
553 * handles {@link Exception Exceptions}.
554 * @return true if the pattern formats any information from exceptions.
555 */
556 public boolean ignoresThrowable() {
557 return !handlesExceptions;
558 }
559 }